An optical pickup device is used for an optical disk drive which irradiates a disk such as a CD, a DVD, a Blu-ray disc, and an HD-DVD disc with a light beam spot to record and reproduce information made up of pit strings on the recording surface of the disk. An optical pickup device has an objective lens actuator for driving an objective lens used for forming a light beam spot.
In recent years, an optical disk drive focuses a light beam spot by using an objective lens having a high numerical aperture (high NA) and records and reproduces data having been recorded with high densities. Thus, objective lenses having small inclinations relative to disks have been demanded.
In other words, regarding an objective lens actuator, a smaller tilt and a smaller reduction in the aberration of a light beam spot have been demanded. A tilt is a rotary motion made beyond a focusing direction and a tracking direction when a lens holder for holding an objective lens is driven.
Japanese Patent Laid-Open No. 2006-134411 discloses an optical pickup device for reducing a tilt, which is a rotary motion made other than a focusing direction and a tracking direction when a lens holder is driven, along with the configuration of a typical objective lens actuator.
First, the configuration of the typical objective lens actuator will be described below in accordance with an accompanying drawing. FIG. 7 is a perspective view showing the typical objective lens actuator according to the prior art. As shown in FIG. 7, an objective lens 51 is held by a lens holder 52, on which terminal plates 53 are fixed.
A fixed substrate 59 is fixed on a fixed part 57. One end 54b of each of a plurality of wires 54 serving as suspension members is fixed by soldering with solder 56. The other end 54a of each of the plurality of wires 54 is fixed to the terminal plates 53 by soldering with solder 55.
The objective lens 51, the lens holder 52 and the terminal plates 53 are formed integrally and constitute a moving part while being supported by the fixed substrate 59 with elasticity through the wires 54. The fixed part 57 has gaps serving as gel holder parts 58. The gaps are filled with damping gel, and the damping gel damps the primary mode vibration of the moving part.
The moving part including the lens holder 52 can be driven in the direction of arrow Fo which is a focusing direction and in the direction of arrow Tr which is a tracking direction. The fixed part has a magnetic flux supply device (not shown) made up of a magnet and a yoke, and a plurality of coils (not shown) are fixed on the lens holder. By energizing the coils through the plurality of wires 54, the objective lens 51 can be driven in a desired direction.
Generally, as shown in FIG. 7, the terminal plates 53 are disposed in parallel with the extension direction of the wires 54. A distance from the end of the solder 55 provided on the terminal plates 53 to the end of the fixed substrate 59 is an effective length L of the plurality of wires 54.
The terminal plates 53 have lands for energizing the ends of the coils (not shown). The state of the lands is shown in FIGS. 8 and 9. FIG. 8 is a side view showing the terminal plate of the prior art. FIG. 9 is a simplified plan view showing the shape of solder on the terminal plate of the prior art.
As shown in FIG. 8, the wires 54 are fixed to the terminal plate 53 by soldering with the solder 55 at a predetermined pitch P. On the terminal plate 53, the lands for energizing the ends of the coils are formed and solder 60 is provided on each of the lands. In this configuration, the terminal plate 53 and the wires 54 are disposed in parallel with each other (disposed in parallel in plan view, to be specific, the surface of the terminal plate 53 and the extension direction of the wires 54 are in parallel with each other). Thus as shown in FIG. 8, the lands are disposed such that the wires 54 and the solder 60 do not intersect each other in side view. In other words, the pitch P between the wires 54 is determined so as to secure a space for the solder 60 for energizing the ends of the coils (not shown).
As shown in FIG. 9, the solder 55 and the solder 60 are formed so as to protrude on the terminal plate 53. Further, the end face position of the substantially hemispherical shape of the solder 55 varies with fluctuations in the amount of solder during soldering and the variations result in a variation ΔL in the effective lengths L of the wires 54.
The foregoing explanation described the configuration of the typical objective lens actuator according to the prior art. In Japanese Patent Laid-Open No. 2006-134411, a technique using a conductive adhesive is disclosed instead of a fixing method using the solder 55 and the solder 56. The main configuration is substantially the same.